Device to measure diameter and thread pitch of a screw



W. MOSS Aug. 13, 1968 DEVICE TO MEASURE DIAMETER AND THREAD PITCH OF ASCREW Filed June 28, 1966 2 Sheets-Sheet l Aug. 13, 1968 w. MOSS3,396,472

DEVICE TO MEASURE DIAMETER AND THREAD PITCH OF A SCREW Filed June 28,1966 2 Sheets-Sheet 2 United States Patent 3,396,472 DEVICE T0 MEASUREDIAMETER AND THREAD PITCH OF A SCREW Wilfred Moss, P.O. Box 255, SouthDuxbury, Mass. 02374 Filed June 28, 1966, Ser. No. 561,285 9 Claims.(Cl. 33-199 This invention relates to a device that measures diameterand thread pitch of a screw, bolt or the like.

One object of my invention is to provide a device that simultaneouslygives a reading of the diameter and thread pitch (number of threads perinch) of a screw-threaded member by the simple movement of placing thelatter member in an opening in my device and rotating a threaded discinto contact with its threads.

Another object is to provide my device with an indicating arm and discoperably coordinated so that movement of the disc moves the arm tothereby simultaneously obtain two readings, namely, diameter and threadpitch or number of threads per inch.

A further object is to provide such a device formed of parts that areinexpensive to manufacture and simple to assemble that provide anoperative device.

The foregoing and other objects which will appear as the nature of theinvention is better understood, may be accomplished by a construction,combination and operative arrangement of parts such as in disclosed bythe drawing. The nature of the invention is such as to render itsusceptible to various changes and modifications, and therefore, I amnot to be limited to the construction disclosed by the drawing, nor tothe particular parts described in the specification; but am entitled toall such changes therefrom as fall within the scope of my claims.

In the drawing:

FIG. 1 is a front elevational view of my device.

FIG. 2 is a top plan view of my device.

FIG. 3 is an enlarged plan view of the disc used in my device.

FIG. 4 is an enlarged, sectional view taken on the line 4-4 of FIG. 1.

FIG. 5 is an enlarged, fragmentary view on an exaggerated scale of aportion of said disc.

As illustrated, I provide supporting means having a front plate 12 whichhas a cut-out 14 at the right side to provide visibility as laterexplained. This plate 12 has a pivot hole 16 and adjacent the left sidethereof is a slot 18 that extends vertically as shown in said FIG. 1. Arectangular cut-out 20 in said means 10 is provided at the lower leftside intermediate the top and bottom, the lower border line of whichprovides a guide or rest 22 to receive a screw-threaded member S to bemeasured as later explained.

Said supporting means has a back plate 26 that is spaced from said frontplate 12 slightly by spacers 27, and it has indicia 28 thereon at theright side to indicate the diameters of different screw-threaded malemembers S as later explained. Said back plate 26 has a pivot hole 30that aligns with said hole 16 and a slot 32 similar to and that alignswith said slot 18 when said supporting plates 12 and 26 are assembled.

A disc gauge 36 extends from one side extremity of said supporting meansand into said opening 20, and it has a hole 38 in the center and at theperiphery there are threads 42 in different portions thereof and ofdifferent sizes that correspond with the different sizes of the threadsof a threaded member S to be gauged or measured. Said disc gauge 36 isshown on its face as a polygon divided into triangular portions orsectors 44, each of which extends from the center thereof to a straightline at the periphery. Said screw-threaded member S makes interfittingcontact with said threads 42 of one of the triangular portions 44 whenbeing measured to determine its thread pitch and diameter.

To determine diameter of said member S I provide an indicator arm 50having a pointed portion 52 at one end which extends laterally to apoint adjacent said back plate indicia 28. Said arm has a hole 54therethrough opposite said holes 30 and 16 and a pivot pin or rivet 56passes through said holes 16, 54 and 30 so that some rotation of saidarm is permitted. Another hole 58 in said arm 51 aligns with said slot18, holes 38 and 58 and slot 32. A pin or rivet 60 thereby rotatablyconnects said disc 36 to said arm and both said plates 12 and 26.

In operation, a screw-threaded member S is placed in the opening 20,resting on said guide or rest 22 bordering said rectangular opening.Said disc 36 along with said arm 50 are drawn downwardly in said slots18 and 32 until said disc is close to or slightly contacts said memberS. Then said disc is rotated until the threads 42 that mesh or interfitthe threads of member S are reached. Then the indicia 46 directlyopposite or above said member S is noted which gives the thread pitch ornumber of threads per inch. Simultaneously the indicia 28 at the farright, that said arm pointed portion 52 is now opposite, gives thediameter of said member S.

For instance, in said FIG. 1, the periphery of the disc sector portionmarked with the indicia 18P, being opposite said member S, and thethreads interfitting, the thread pitch is 18. The vertical or linearmovement of the disc 36 also moved said arm 50 and at the termination ofthis disc movement the pointed portion 52 is opposite the numeral 7 onsaid back plate indicia 28. This gives the reading of the diameter as 1as well as that of the thread pitch.

The distance from the center 38 of said disc 36 to the outside point orcrest 58 of a plurality of disc threads may be the same when my deviceis used to obtain thread pitch and diameter of a relatively small rangeof sizes of coarse threaded members S such as 13F to 18F, for instance.This is so because the position of said indicator arm 50 is onlyslightly affected by very small differences in thread pitch and willgive an accurate reading of diameter even though the pointed portion 52does vary its position slightly.

When the thread pitch range reaches to relatively high numbers, asoccurs in fine threaded members, the distance from said disc center 38to the outer crest 58 of the disc threads must vary in accordance withthe different sizes of threads. In a 13 pitch thread, for instance, thedistance may measure 1.000 inch, while in a 48 pitch thread the distancemay rneasure .963 inch as illustrated in said FIG. 5. But the distancefrom said disc center 38 to the root or inner crest 60 should beconstant in the various sizes as shown in said FIG. 5. This variation isnecessary to compensate for substantial differences in thread depth indifferent sizes of threaded members since the coarser threads are deeperthan the finer ones as illustrated in said FIG. 5. By compensating forthis difference at the periphery of said disc 36 the diameter readingobtained will be accurate whereas it would be inaccurate otherwise.

Thus whether the threads of a member S are 13 pitch or 48 pitch, uponrotation of the disc to the point where the threads thereon interfitwith those of said member 3, the diameter reading will be the samebecause of said compensation.

What I claim is:

1. A device to determine diameter and thread pitch of a screw-threadedmember comprising supporting means having an opening intermediate thetop and bottom thereof and having a slot therethrough, a disc extendinginto said opening having a plurality of straight edges. at

the periphery thereof extending angularly to each other, and threadsformed in said edges, an indicating arm, first means rotatablyconnecting said arm and said supporting means, second means extendingthrough said slot, arm and disc rotatably connecting said disc to saidarm and to said supporting means, said second means being slidable insaid slot whereby said disc may be moved about said first means, saida-rm extending from and beyond said disc.

2. A device as set forth in claim 1, the threads in one said edgevarying in pitch from those in another.

3. A device as set forth in claim 1, said supporting means havingindicia thereon indicating different diameters of a said member, saidarm extending to a point adjacent said indicia.

4. A device as set forth in claim 1, said supporting means having afront plate and a back plate spaced therefrom, said disc and armextending between said plates.

5. A device as set forth in claim 4, said back plate having indiciamarked thereon adjacent a side extremity thereof, said front platehaving a cut-out at a side extrernity thereof so positioned as to makesaid indicia visible.

6. A device as set forth in claim 4, said disc extending laterallybeyond said supporting means.

7. A device as set forth in claim 1, the face surface of said dischaving marking lines thereon dividing said surface into triangularportions from the center of said disc to the periphery thereof, eachsaid triangular portion having said threads at the periphery thereof,the pitch of 4 threads of one said triangular portion varying from thatof another said triangular portion, each said triangular portion havingindicia thereon within its marking lines indicating threads per inchcorresponding to the thread pitch at its periphery.

8. A device as set forth in claim 2, the distance from the center ofsaid disc to the outer crests of said threads varying between one saidedge and another, the coarser threads lextending farther outwardly thanthe finer threads.

9. A device as set forth in claim 8, the distance from the center ofsaid disc to the inner crests of said threads being substantially thesame.

References Cited UNITED STATES PATENTS 1,465,920 8/1923 Francis 33-1682,027,217 1/1936 Zerkle 33-199 2,210,560 8/1940 Allen et a1. 331992,664,638 1/1954- Storey 33-168 2,901,829 9/1959 Lucas 33--168 2,933,8174/1960 Puckett et a1. 33-168 OTHER REFERENCES Tool & Die Journal, June1949, p. 130, A New Model Gear Gage (copy in group 283).

LEONARD FORMAN, Primary Examiner.

JOEL M. FREED, Assistant Examiner.

1. A DEVICE TO DETERMINE DIAMETER AND THREAD PITCH OF A SCREW-THREADEDMEMBER COMPRISING SUPPORTING MEANS HAVING AN OPENING INTERMEDIATE THETOP AND BOTTOM THEREOF AND HAVING A SLOT THERETHROUGH, A DISC EXTENDINGINTO SAID OPENING HAVING A PLURALITY OF STRAIGHT EDGES AT THE PERIPHERYTHEREOF EXTENDING ANGULARLY TO EACH OTHER, AND THREADS FORMED IN SAIDEDGES, AN INDICATING ARM, FIRST MEANS ROTATABLY CONNECTING SAID ARM ANDSAID SUPPORTING MEANS, SECOND MEANS EXTENDING THROUGH SAID SLOT, ARM ANDDISC ROTATABLY CONNECTING SAID DISC TO SAID ARM AND TO SAID SUPPORTINGMEANS, SAID SECOND MEANS BEING SLIDABLE IN SAID SLOT WHEREBY SAID DISCMAY BE MOVED ABOUT SAID FIRST MEANS, SAID ARM EXTENDING FROM AND BEYONDSAID DISC.